Year of Award


Document Type


Degree Type

Doctor of Philosophy (PhD)

Degree Name

Organismal Biology, Ecology, and Evolution

Department or School/College

Division of Biological Sciences

Committee Chair

Ragan M. Callaway

Commitee Members

Dean E. Pearson, Cara R. Nelson, Anna Sala, Lloyd R. Stark


biotic soil crusts, bryophyte, desiccation-rehydration, facilitation, moss, resource pulses


University of Montana


Non-vascular mosses are known to be ecologically influential and structure communities through their physiological and physical attributes. My dissertation had two objectives. The first goal was to understand how fundamental differences in the physiology of mosses might drive much of their ecological impact. Mosses frequently and rapidly fluctuate between dehydration and rehydration. During these transitions, the cellular integrity of moss is compromised and intra-cellular contents (carbohydrates, amino acids, and ionic compounds) are released. Thus during wet-dry transition periods, mosses have the potential to release pulses of nutrients which may have important effects on other species. However, few studies have explored these bryotic pulses in the context of communities and ecosystems. This first part of my dissertation worked to fill this gap by addressing: 1) How the unique physiology of mosses directly influenced ecosystem level processes? And 2) If bryotic pulses regulated biotic interactions and nutrient availability? The second objective of my dissertation was to understand the community level effects of mosses in semi-arid grasslands. Though mosses are abundant in many ecosystems ranging in climate from mesic to arid, our current understanding of their role in dryland systems is limited. I used a positive spatial association between native mosses and an exotic forb to investigate direct and indirect interactions between these co-occurring plants. I also considered the potentially widespread effects of moss as a component of biotic soil crusts on plant establishment in intermountain grasslands.



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